Flexible and expansible threaded joint



Feb. 15, 1955 J. w. M DONNELL FLEXIBLE AND EXPANSIBLE THREADED JOINTFiled June 16, 1951 w iwa IAIIIIIIIIIIIIAVIWIflIAII/IIIIJZVIIIAIAVIIAINVENTOR. James W MFDonne/l %4/-'- lTTOE/VE Y5 @426 F IE PatentedFeb.15, 1955 FLEXIBLE AND EXPANSIBLE THREADED JOINT James W. McDonnell,Walnut Creek, Calif.

Application June 16, 1951, Serial No. 231,985

3 Claims. (Cl. 285-71) This invention relates generally to apparatus forforming ducts in concrete walls or like structures.

In the construction of concrete buildings it is common practice toprovide metal piping or conduit for receiving the necessary electricalwiring. The conduit must be placed in the walls before the concrete ispoured, and thereafter becomes a permanent part of the structure. Suchmetal conduit adds considerably to the cost of the structure, due notonly to the material required, but also to the relatively large amountof labor involved in positioning the conduit before the concrete ispoured.

It is an object of the present invention to provide practical apparatuswhich can be used to provide ducts forwiring and the like, in concretestructures, without the use of conventional metal conduit or piping.

Another object of the invention is to provide apparatus of,\the--above,-- character whichcan be readily removed from thehardenedconcrete and reused as required.

Another object of the invention is to provide apparatus of the abovecharacter making use of an inflated resilient tube or hose, whichprovides improved means for engaging one end of the tube or hose forremoving it from the concrete structure.

Additional objects of the invention will appear from the followingdescription in which the preferred embodiment has been set forth indetail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure 1 is a side-elevational view in section, schematicallyillustrating a concrete wall with my apparatus applied to the same.

Figure 2 is a cross-sectional detail showing the conduit formed by useof my apparatus.

Figure 3 is a large cross-sectional view illustrating the device whichis applied to one end of the hose, for facilitating removal of the same.

Figure 4 is a side elevational view of the device illustrated in Figure3.

Figure 5 is a cross-sectional view illustrating a type of coupling whichI can use for joining two or more hose sections together.

Figure 6 is an enlarged cross-sectional detail illustrating theconstruction of the coupling illustrated in Figure 5.

In Figure 1 of the drawing 1 have illustrated a concrete wall 10 whichis being cast between the side forms 11 and 12. It is assumed in thisinstance that one desires to provide a duct for electrical wiringbetween the two spaced outlet boxes 13 and 14.

Instead of providing conventional metal conduit or piping between theboxes 13 and 14, I provide a tube 16 of suitable resilient material,such as resilient synthetic rubber. This tube is extended between theoutlet boxes 13 and 14 before the concrete is poured, and end portionsmay extend a convenient distance from the boxes as illustrated. Aclosure 17 is shown applied to one end of the tube, and'to the other endof the tube there is applied a special device 18.

It may be mentioned at this point that after the resilient tube has beeninstalled in the concrete form, it is inflated by air under pressure, tocause it to increase in diameter. The increase may not be great, as forexample from two to five percent. Thus assuming that one desires to forma duct of about one inch in diameter, a tube having a normal externaldiameter of one inch can be inflated to a diameter ranging from say 1%to 1%,; inches. The

tubing employed should be such that it can be readily increased indiameter by applied internal pressure. Thus a tubing should be used thatdoes not include metal, fabric or cord reinforcing tending to prevent anincrease in diam- 5 eter. With certain types of synthetic rubber,reinforcement can be omitted in entirety or, if employed, it should besuch that it does not interfere with a limited amount of circumferentialstretch. a

After the concrete has been poured and has hardened, the tube isdeflated and then pulled lengthwise from the duct. The decrease indiameter accompanying deflation of the tube serves to break any adhesionbetween the smooth exterior surface of the tube and the concrete, andprovides sufficient clearance for pulling the tube lengthwise from theduct. The special device 18 illustrated in Figure 1 facilitates theoperation of pulling the tube from the duct, and in addition, as will bepresently explained, it may be provided with a fitting for introducingor venting air from the tube.

Referring now to Figures 3 and 4, the device consists of a tubular shell21 which is adapted to fit within and around the end portion 22 of thetube 16. Surrounding the tube portion 22 there is a contractible wiremesh assembly 23. One end portion of the wire mesh assembly is shownattached to the clamping ring 24, which can be contracted upon the tubeby tightening the screw or bolt 26. The other end portion of the wiremesh assembly is shown embracing the sphericallycontoured member 27,which is carried by the rod 28. The rod 28 forms in effect a pullmember,and is shown provided with the .eye 29, for-engagement with supplementalmeans, such as a pull cable, rope, or the like. The rod 28 is preferablymovably attached to the shell 21. Thus the shell is shown provided withan end wall 31 which has an opening to slidably accommodate the rod 28.The fit between these parts is preferably sealed as by means of aresilient rubber 0 ring 32. A helical spring 33 acts against a collar orwasher 34 which is attached to the inner end of the rod 28, and servesto yieldably urge the rod 28 toward the left as viewed in Figure 3. Asuitable fitting 36 is shown attached to the rod 28 for introducing orventing air from the tube. This fitting is in communication with theinterior of the shell 21 by way of duct 37 in the rod 28.

The wire mesh assembly 23 is generally tubular in form, and consists ofthe interwoven spring wires 38 and 39, which extend helicoidally aboutthe axis of the device.

The device in Figures 3 and 4 operates as follows: Before being attachedto the end of the resilient tube, the wire mesh assembly 23 is relaxedand therefore can be readily slipped over the end of the tube. Inapplying the device to the tube, the shell 21 is slipped into the tubewhile at the same time the wire mesh is guided over the exterior surfaceof the tube. Thereafter the clamp 24 is tightened to grip the tube.Assuming that the device is applied before the concrete is cast, thenair can be applied to the interior of the tube through the fitting 36,to secure the desired degree of inflation. After the concrete has beenpoured and hardened, air is vented from the tube, closure 17 is removed,and then pulling force is applied to the eye 29. Application of suchpulling force is accompanied by movement of the pull member 28 relativeto the shell 21, against the compression of spring 33, and longitudinalstretch is applied to the wire mesh assembly 23 to cause the same totightly contract upon the tube portion 22. The resulting tight grip uponboth the outer and inner surfaces of the tube serves to adequatelytransmit force to the main length of the tube, thus causing the tube tobe withdrawn from the concrete duct. After the tube has been Withdrawnthe device of Figures 3 and 4 can be readily removed from the tube,because when pull is no longer applied to the eye 29, the wire mesh 23relaxes, and upon loosening the clamp 24, the device slips relativelyfreely from the tube.

Figure 2 illustrates the type of duct which can be formed by use of myapparatus, and which is particularly suitable for accommodatingelectrical wiring. In this instance a duct 41 has been formed by removalof -a,'ro2,199

the tube 16, and this duct is suitable for receiving electrical wiring,the same as conventional metal wiring conduit.

In instances where extended ducts are desired it is possible to use twoor more sections of resilient tubing,

suitablycoupled together. However the coupling means should be such thatits diameter is increased when the tube is inflated, thus making itpossible to pull the coupling from the duct after a concrete pouringoperation. In the coupling construction illustrated in Figure 5, the twotubular sections 16a and 16b are provided with end portions 42a and 42bwhich are in threaded engagement. As shown particularly in Figure 6, theportion 42a can be tapered, portion 42b can be similarly made divergentto facilitate making quick connection. The threads 43 formed upon theportion 42a can be rounded as illustrated in Figure 6, and can bereinforced by a spirally wound spring metal ribbon 44. The cooperatingthreads 46 can be similarly rounded, and reinforced by the spring metalribbon 47;: It will be noted that the threads 43 and 46 in Figure 6 aremolded from the same resilient rubber material as is employed in makingthe resilient tubes. The spring metal ribbons 44 and 47 providesufficient enforcement to prevent the coupled sections from pullingapart, while at the same time permitting some expansion of the couplingwhen the tube is inflated;

It will be evident that my invention can be used to provide extendedducts for various purposes, as for example to serve as temporary watersupply or gas flow passages, as well as for wiring. Such ducts mayextend about corners or wall obstructions without interfering with orweakening the basic wall design.

I claim: a

l. Radially expansible coupling means for radially expansible tubesections formed of resilient material, comprising tubular end portionsformed integral with the walls of the tube sections, one of saidportions having an interior surface of larger diameter than the interiorsurfaces of said tube sections and the other of said portions having anexterior surface of smaller diameter than the exterior surfaces of saidtube sections, helicoidal threads formed of resilient material on saidinterior and exterior surfaces of said end portions and adapted tomutually interengage to form a fluid-tight connection, and helicoidalspring metal members embedded in said threads, said spring metal membershaving radially overlapping portions when said threads are interengaged,said interengaged coupling means having the same external and internaldiameters as said tube sections whereby said coupling means may expandradially to substantially the same extent as said tube sections.

2; Radially expansible coupling means as defined in claim 1 wherein saidspring metal members are flattened in an axial direction whereby theirradial width is substantially greater than their axial thickness.

3. Radially expansible coupling means as defined in claim 1 wherein themating interior and exterior surfaces of said end portions are generallyconical, tapering inwardly from the outer end of said one of saidportions.

References Cited in the file of this patent UNITED STATES PATENTS1,538,902 Murray May 26, 1925 1,600,353 Nose Sept. 21, 1926 1,679,698Weydert Aug. 7, 1928 2,271,931 Williamson Feb. 3, 1942 2,366,067 SmithDec. 26, 1944 2,434,358 Frank Jan. 13, 1948 FOREIGN PATENTS 228,740Great Britain Feb. 12, 1923 like

